CN113036776A - Draw-out type low-voltage switch cabinet power factor stepless compensation device and method - Google Patents

Draw-out type low-voltage switch cabinet power factor stepless compensation device and method Download PDF

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CN113036776A
CN113036776A CN202110241853.4A CN202110241853A CN113036776A CN 113036776 A CN113036776 A CN 113036776A CN 202110241853 A CN202110241853 A CN 202110241853A CN 113036776 A CN113036776 A CN 113036776A
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phase
relay
power factor
solid
interphase
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CN113036776B (en
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韩雪
肖朋
韩卫俭
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Runeng Shandong Electric Power Technology Co ltd
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Runeng Shandong Electric Power Technology Co ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
    • H02J3/1835—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02B—BOARDS, SUBSTATIONS OR SWITCHING ARRANGEMENTS FOR THE SUPPLY OR DISTRIBUTION OF ELECTRIC POWER
    • H02B11/00—Switchgear having carriage withdrawable for isolation
    • H02B11/12—Switchgear having carriage withdrawable for isolation with isolation by horizontal withdrawal
    • H02B11/173—Switchgear having carriage withdrawable for isolation with isolation by horizontal withdrawal drawer type
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase networks
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/30—Reactive power compensation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks

Abstract

The invention provides a draw-out type low-voltage switch cabinet power factor stepless compensation device and a draw-out type low-voltage switch cabinet power factor stepless compensation method, wherein a first interphase relay, a second interphase relay and a third interphase relay are arranged, the connection relation of the first interphase relay, the second interphase relay and the third interphase relay can realize the connection of a capacitor bank A, a capacitor bank B and a capacitor bank C in pairs, and when the three-phase power factor is unbalanced or seriously unbalanced, the three-phase access capacitance value is adjusted by controlling the connection and disconnection of the first interphase relay, the second interphase relay and the third interphase relay, so that the power interphase compensation is realized; the duty ratio of the solid-state relay A, the solid-state relay B and the solid-state relay C is controlled by adopting a closed-loop control principle to adjust the access capacitance value, and the stepless adjustment of each access capacitance is realized, so that the stepless adjustment of the power factor is realized.

Description

Draw-out type low-voltage switch cabinet power factor stepless compensation device and method
Technical Field
The invention relates to the field of low-voltage switch cabinet power factor compensators, in particular to a draw-out type low-voltage switch cabinet power factor stepless compensation device and a draw-out type low-voltage switch cabinet power factor stepless compensation method.
Background
The low-voltage switch cabinet is widely applied to power transmission, power distribution and the like in the fields of power plants, chemical industry, metallurgy, high-rise buildings and the like, and because the inductive load is connected and reactive power is injected into a power grid, the power factor of the power grid is reduced, and the quality and the efficiency of electric energy are reduced. The parallel capacitors can improve the power factor of a power grid, and therefore, a capacitor array is arranged in the traditional power factor adjusting device, and the capacitor array is adjusted and incorporated into the traditional power factor adjusting device through a relay, so that the power factor of the power grid is improved, but the parallel capacitors can increase the cost of the device and make the structure of the device complex, and on the other hand, the stepless adjustment of the power factor is difficult to realize. Therefore, in order to solve the above problems, the present invention provides a power factor stepless compensation device and method for a draw-out low-voltage switch cabinet, which adopts power factor phase compensation, realizes stepless regulation of the power factor by controlling the duty ratio of a solid-state relay, and realizes precise regulation by feedback compensation of the duty ratio of the solid-state relay.
Disclosure of Invention
In view of the above, the invention provides a draw-out type low-voltage switch cabinet power factor stepless compensation device and a draw-out type low-voltage switch cabinet power factor stepless compensation method, which adopt power factor interphase compensation, realize stepless regulation of a power factor by controlling the duty ratio of a solid-state relay, and realize accurate regulation by feedback compensation of the duty ratio of the solid-state relay.
The technical scheme of the invention is realized as follows: on one hand, the invention provides a draw-out type low-voltage switch cabinet power factor stepless compensation device which comprises a controller, a capacitor bank A, a capacitor bank B, a capacitor bank C, a solid-state relay A, a solid-state relay B, a solid-state relay C, a first interphase relay, a second interphase relay and a third interphase relay;
the inlet wire end of the phase A of the low-voltage switch cabinet is connected with the input end of the capacitor bank A through the solid-state relay A, and the output end of the capacitor bank A is connected with a zero line; the input end of the phase B of the low-voltage switch cabinet is connected with the input end of the capacitor bank B through the solid-state relay B, and the output end of the capacitor bank B is connected with a zero line; the input end of the phase C of the low-voltage switch cabinet is connected with the input end of the capacitor bank C through the solid-state relay C, and the output end of the capacitor bank C is connected with a zero line;
the first interphase relay is connected in parallel between the input end of the capacitor bank A and the input end of the capacitor bank B; the second phase relay is connected in parallel between the input end of the capacitor bank B and the input end of the capacitor bank C; the third phase-to-phase relay is connected in parallel between the input end of the capacitor bank A and the input end of the capacitor bank C;
the controller controls the on-off of the solid-state relay A, the solid-state relay B, the solid-state relay C, the first interphase relay, the second interphase relay and the third interphase relay.
On the basis of the technical scheme, the power factor compensation drawer is preferably further included;
the power factor stepless compensation device is arranged in the power factor compensation drawer; the power factor compensation drawer is installed in a push-pull mode.
On the other hand, the invention provides a draw-out type low-voltage switch cabinet power factor stepless compensation method, which comprises the following steps:
s1, connecting the lines according to the connection mode of the low-voltage switch cabinet power factor stepless compensation device;
s2, the controller carries out fuzzy classification according to the difference value of the target power factor and the actual power factor of the three phases at the inlet end of the low-voltage switch cabinet in each control period, and judges the balance condition of the three-phase power factors according to the simulation classification;
s3, when the three-phase power factor is unbalanced or seriously unbalanced, controlling the on-off of a first interphase relay, a second interphase relay and a third interphase relay based on a power factor stepless regulation fuzzy rule to realize three-phase power factor interphase compensation;
s4, obtaining a compensation duty ratio of the corresponding phase solid state relay based on the target duty ratio and the actual target duty ratio of the solid state relay A, the solid state relay B and the solid state relay C, performing feedback compensation on the duty ratio of the corresponding phase solid state relay based on the compensation duty ratio to realize accurate adjustment of the duty ratio of the phase solid state relay, and further realizing stepless adjustment of the three-phase power factor.
On the basis of the above technical solution, preferably, the specific rule of fuzzy classification in S2 is:
the difference between the actual power factor of the A phase and the target power factor is recorded as delta lambdaaIt is divided into three fuzzy values H, M, L when the delta lambda isa∈(a1,a2]When, delta lambdaaIs L; when delta lambdaa∈(a2,a3]When, delta lambdaaIs M; when delta lambdaa∈(a3,a4]When, delta lambdaaIs H; a1, a2, a3 and a4 are constants between (0 and 1), and a1 < a2 < a3 < a 4;
the difference between the actual power factor of the B phase and the target power factor is recorded as delta lambdabIt is divided into three fuzzy values H, M, L when the delta lambda isb∈(b1,b2]When, delta lambdabIs L; when delta lambdab∈(b2,b3]When, delta lambdabIs M; when delta lambdab∈(b3,b4]When, delta lambdabIs H; b1, b2, b3 and b4 are constants between (0 and 1), and b1 is more than b2 and more than b3 is more than b 4;
the difference between the actual power factor of the C phase and the target power factor is recorded as delta lambdacIt is divided into three fuzzy values H, M, L when the delta lambda isc∈(c1,c 2]When, delta lambdacIs L; when delta lambdac∈(c2,c3]When, delta lambdacIs M; when delta lambdac∈(c3,c4]When, delta lambdacIs H; c1, c2, c3 and c4 are constants between (0 and 1), and c1 < c2 < c3 < c 4.
Based on the above technical means, preferably, (Δ λ) is known in S2 based on fuzzy classification rulesa，Δλb，Δλc) There are 27 permutation combinations; wherein, when Δ λa，Δλb，ΔλcAll being a combination of fuzzy values of L, or Δ λa，Δλb，ΔλcWhen the value of (1) is any one combination of two value conditions of the M fuzzy value and the H fuzzy value, judging that the three-phase power factor is balanced;
when delta lambdaa，Δλb，ΔλcWhen two terms are L fuzzy values and the other term is H, the three-phase power factor is judged to be seriously unbalanced;
when delta lambdaa，Δλb，ΔλcIn the case of the remaining combinations, the determination factor is unbalanced.
On the basis of the above technical solution, preferably, the method for implementing phase-a power factor inter-phase compensation in S3 includes: in the initial state, the controller controls the solid state relay A to be switched on, the solid state relay B and the solid state relay C to be switched off, and equivalent electricity of the phase A is switched onThe capacitance value is C, and the capacitance value of the capacitor group A is CaThe capacitance value of the capacitor group B is Cb, and the capacitance value of the capacitor group C is Cc；
When the three-phase power factor is balanced, the first interphase relay, the second interphase relay and the third interphase relay are all switched off, and C is equal to Ca(1)；
When the three-phase power factor is seriously unbalanced, the first phase-to-phase relay and the second phase-to-phase relay are switched on, the third phase-to-phase relay is switched off, and C is equal to Ca+Cb+Cc(2)；
When three-phase power factor is unbalanced, the make-and-break combination of first interphase relay, second interphase relay and third interphase relay has 2, the first: the first phase relay is switched on, the second phase relay and the third phase relay are switched off, and C is equal to Ca+Cb(3) (ii) a And the second method comprises the following steps: when the first phase relay and the second phase relay are switched off and the third phase relay is switched on, C is equal to Ca+Cc(4)。
On the basis of the above technical solution, preferably, S4 specifically includes the following steps:
s201, calculating target duty ratios of the single-phase solid-state relay based on the single-phase power triangle and the phase capacitance reactive power formula, and obtaining the target duty ratios of the solid-state relay A, the solid-state relay B and the solid-state relay C by adopting the same calculation principle;
s202, obtaining a three-phase compensation coefficient based on a power factor stepless regulation fuzzy rule, wherein the product of the single-phase compensation coefficient and the difference value of the actual power factor and the target power factor of the phase is the compensation duty ratio of the phase, and further the compensation duty ratios of a solid-state relay A, a solid-state relay B and a solid-state relay C are obtained;
s203, the sum of the target duty ratio of the single-phase solid-state relay and the compensation duty ratio of the single-phase solid-state relay is the actual target duty ratio of the phase solid-state relay, and the controller accurately controls the phase solid-state relay based on the actual target duty ratio, so that stepless regulation of the three-phase power factor is achieved.
On the basis of the above technical solution, preferably, the target duty ratio of the single-phase solid-state relay in S201 is:
Figure BDA0002962500550000051
wherein tonThe on-time of a solid state relay of a certain phase in a period T is shown, P is the active power of the phase,
Figure BDA0002962500550000052
for the actual phase angle of the phase,
Figure BDA0002962500550000053
and U is the phase target phase angle, U is the effective value of the phase voltage, w is the angular velocity of the phase voltage current, and C is the phase access equivalent capacitance value.
On the basis of the above technical solution, preferably, the three-phase compensation coefficients in S202 are respectively:
when delta lambdaaWhen is L, kaIs taken as kal(ii) a When delta lambdaaWhen is M, kaIs taken as kam(ii) a When delta lambdaaWhen is H, kaIs taken as kah；kaIs A phase compensation coefficient; k is a radical ofal、kam、kahIs constant and 0 < kal＜kam＜kah；
When delta lambdabWhen is L, kbIs taken as kbl(ii) a When delta lambdabWhen is M, kbIs taken as kbm(ii) a When delta lambdabWhen is H, kbIs taken as kbh；kbIs a B-phase compensation coefficient; k is a radical ofbl、kbm、kbhIs constant and 0 < kbl＜kbm＜kbh；
When delta lambdacWhen is L, kcIs taken as kcl(ii) a When delta lambdacWhen is M, kcIs taken as kcm(ii) a When Δ λ c is H, kcIs taken as kch；kcC phase compensation coefficient; k is a radical ofcl、kcm、kchIs constant and 0 < kcl＜kcm＜kch。
Compared with the prior art, the draw-out type low-voltage switch cabinet power factor stepless compensation device and the method have the following beneficial effects:
(1) the power interphase compensation method comprises the steps that a first interphase relay, a second interphase relay and a third interphase relay are arranged, connection relation among a capacitor bank A, a capacitor bank B and a capacitor bank C can be achieved in a pairwise mode, when three-phase power factors are unbalanced or seriously unbalanced, the three-phase access capacitance value is adjusted by controlling the connection and disconnection of the first interphase relay, the second interphase relay and the third interphase relay, and then power interphase compensation is achieved;
(2) the method comprises the steps of carrying out fuzzy classification on the difference value between a target power factor and an actual power factor of three phases, judging the balance condition of the three-phase power factors according to simulation classification, carrying out three-phase power interphase compensation according to the balance condition of the three-phase power factors, determining the compensation coefficients of a solid-state relay A, a solid-state relay B and a solid-state relay C, and providing a data base for accurately controlling the solid-state relay A, the solid-state relay B and the solid-state relay C;
(3) the access capacitance is adjusted by controlling the duty ratio of the solid-state relay A, the solid-state relay B and the solid-state relay C, and the stepless adjustment of the access capacitance is realized, so that the stepless adjustment of the power factor is realized;
(4) and a compensation coefficient and a compensation duty ratio of the three-phase solid-state relay are obtained based on a power factor stepless regulation fuzzy rule, and the duty ratio of the solid-state relay A, the solid-state relay B and the solid-state relay C is controlled by a closed-loop control method of compensation duty ratio feedback regulation, so that the accurate control of the duty ratio of the solid-state relay is realized.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a structural diagram of a draw-out type low-voltage switch cabinet power factor stepless compensation device of the invention;
FIG. 2 is a power triangle before and after the A-phase power factor is improved in the method for stepless compensation of power factor of the draw-out type low-voltage switch cabinet according to the present invention;
FIG. 3 is a schematic diagram of the compensation of the duty ratio of a solid relay A in the stepless power factor compensation method for the draw-out type low-voltage switch cabinet according to the invention;
fig. 4 is a fuzzy rule table of power factor stepless regulation in the method for power factor stepless compensation of the draw-out type low-voltage switch cabinet of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
Example 1
As shown in fig. 1, the drawout low-voltage switch cabinet power factor stepless compensation device of the invention comprises a controller, a capacitor bank a, a capacitor bank B, a capacitor bank C, a solid-state relay a, a solid-state relay B, a solid-state relay C, a first interphase relay, a second interphase relay and a third interphase relay.
The input end of the phase A of the low-voltage switch cabinet is connected with the input end of a capacitor bank A through a solid-state relay A, and the output end of the capacitor bank A is connected with a zero line; the input end of the phase B of the low-voltage switch cabinet is connected with the input end of the capacitor bank B through the solid-state relay B, and the output end of the capacitor bank B is connected with a zero line; the input end of the phase C of the low-voltage switch cabinet is connected with the input end of the capacitor bank C through the solid-state relay C, and the output end of the capacitor bank C is connected with a zero line; the first interphase relay is connected in parallel between the input end of the capacitor bank A and the input end of the capacitor bank B; the second phase relay is connected in parallel between the input end of the capacitor bank B and the input end of the capacitor bank C; the third phase-to-phase relay is connected in parallel between the input end of the capacitor bank A and the input end of the capacitor bank C; the controller controls the on-off of the solid-state relay A, the solid-state relay B, the solid-state relay C, the first interphase relay, the second interphase relay and the third interphase relay.
In this embodiment, the front end of each phase of capacitor bank is connected in series with the solid-state relay of the corresponding phase and is merged into the incoming line end of the phase of the low-voltage switch cabinet, and the accessed capacitor can be adjusted only by connecting the solid-state relay of each phase in series with the front end of the corresponding capacitor bank; the connection relation of the first interphase relay, the second interphase relay and the third interphase relay realizes the connection of the capacitor bank A, the capacitor bank B and the capacitor bank C in pairs, so that the size adjustment of a three-phase access capacitor is realized by controlling the on-off of the first interphase relay, the second interphase relay and the third interphase relay, and further the three-phase power interphase compensation is realized.
Preferably, a low-voltage switch cabinet is provided with a power factor compensation drawer, the power factor stepless compensation devices of the embodiment are uniformly distributed in the power factor compensation drawer, and the power factor compensation drawer is installed in a push-pull mode without wiring.
The working principle of the embodiment is as follows: according to the three-phase power factor balance condition, the controller controls the first interphase relay, the second interphase relay and the third interphase relay to be switched on and off, and adjusts the equivalent capacitance value of three-phase access to realize interphase compensation. Taking the phase-to-phase power compensation of the phase A as an example, in an initial state, the controller controls the solid state relay A to be switched on, the solid state relay B and the solid state relay C to be switched off, the equivalent capacitance value of the phase A is recorded as C, the capacitance value of the capacitor bank A is recorded as Ca, the capacitance value of the capacitor bank B is recorded as Cb, and the capacitance value of the capacitor bank C is recorded as Cc;
when the three-phase power factor is balanced, when the first interphase relay, the second interphase relay and the third interphase relay are all switched off, C is Ca;
when the three-phase power factor is seriously unbalanced, the first phase-to-phase relay and the second phase-to-phase relay are switched on, the third phase-to-phase relay is switched off, and C is Ca + Cb + Cc;
when three-phase power factor is unbalanced, have 2 looks relay make-break combinations between looks, the first: the first interphase relay is switched on, the second interphase relay and the third interphase relay are switched off, and C is Ca + Cb; and the second method comprises the following steps: when the first phase relay and the second phase relay are switched off and the third phase relay is switched on, C is Ca + Cc. The meaning of the first on-off combination is to compensate the A phase by using the capacitance values of the A phase and the B phase, and the meaning of the second on-off combination is to compensate the A phase by using the capacitance values of the A phase and the C phase.
The beneficial effect of this embodiment does: through setting up first relay between the phases, relay between second and the relay between the third phase to its relation of connection can realize two liang of connections of electric capacity group A, electric capacity group B, electric capacity group C, when three-phase power factor is uneven or serious unbalance, through the break-make of controlling first relay between the phases, relay between the second and the relay between the third phase, adjust the three-phase and insert the capacitance value size, and then realize the alternate compensation of power.
Example 2
On the basis of embodiment 1, the present embodiment provides a method for stepless compensation of power factor of a draw-out low-voltage switch cabinet, which specifically includes the following steps:
s1, connecting according to the connection mode of the embodiment 1;
s2, the controller carries out fuzzy classification according to the difference value of the target power factor and the actual power factor of the three phases at the inlet end of the low-voltage switch cabinet in each control period, and judges the balance condition of the three-phase power factors according to the simulation classification;
the specific rules of fuzzy classification are as follows:
the difference between the actual power factor of the A phase and the target power factor is recorded as delta lambdaaIt is divided into three fuzzy values H (high), M (middle) and L (low), when the delta lambda isa∈(a1,a2]When, delta lambdaaIs L; when delta lambdaa∈(a2,a3]When, delta lambdaaIs M; when delta lambdaa∈(a3,a4]When, delta lambdaaIs H; a1, a2, a3 and a4 are constants between (0 and 1), and a1 < a2 < a3 < a 4;
the difference between the actual power factor of the B phase and the target power factor is recorded as delta lambdabIt is divided into three fuzzy values H (high), M (middle), L (low)) When Δ λb∈(b1,b2]When, delta lambdabIs L; when delta lambdab∈(b2,b3]When, delta lambdabIs M; when delta lambdab∈(b3,b4]When, delta lambdabIs H; b1, b2, b3 and b4 are constants between (0 and 1), and b1 is more than b2 and more than b3 is more than b 4;
the difference between the actual power factor of the C phase and the target power factor is recorded as delta lambdacIt is divided into three fuzzy values H (high), M (middle) and L (low), when the delta lambda isc∈(c1,c2]When, delta lambdacIs L; when delta lambdac∈(c2,c3]When, delta lambdacIs M; when delta lambdac∈(c3,c4]When, delta lambdacIs H; c1, c2, c3 and c4 are constants between (0 and 1), and c1 < c2 < c3 < c 4.
Based on the fuzzy classification rule, 27 permutation combinations are available (Δ λ a, Δ λ b, Δ λ c), and the 27 permutation combinations are shown in fig. 4. When the values of the delta lambda a, the delta lambda b and the delta lambda c are all the combination of the L fuzzy values or any one of all the combinations of the two values of the M fuzzy value and the H fuzzy value, the three-phase power factor balance is judged without power factor interphase compensation; thus, 9 combinations of three-phase power factor balance are available;
when two terms of the Δ λ a, the Δ λ b and the Δ λ c are L fuzzy values and the other term is a combination of H, determining that the three-phase power factor is seriously unbalanced and needing to compensate one phase of the unbalanced power factor by the three phases; it can be seen that there are 3 combinations of severe imbalance of the three-phase power factor;
when Δ λ a, Δ λ b, Δ λ c are the remaining 15 combinations, the determination factor is unbalanced, and one phase of the power factor imbalance needs to be compensated by two phases.
S3, when the three-phase power factor is unbalanced or seriously unbalanced, controlling the on-off of a first interphase relay, a second interphase relay and a third interphase relay based on a power factor stepless regulation fuzzy rule to realize three-phase power factor interphase compensation;
when the three-phase power factor is unbalanced or seriously unbalanced, power interphase compensation is needed, taking the phase-A power interphase compensation as an example, a specific phase-A power interphase compensation method is as follows: in an initial state, the controller controls the solid state relay A to be switched on, the solid state relay B and the solid state relay C to be switched off, the equivalent capacitance value of the switched-in phase A is recorded as C, the capacitance value of the capacitor bank A is recorded as Ca, the capacitance value of the capacitor bank B is recorded as Cb, and the capacitance value of the capacitor bank C is recorded as Cc. As shown in fig. 4, the first interphase relay, the second interphase relay, and the third interphase relay are switched on and off, where on is represented by 1 and off is represented by 0.
When the three-phase power factor is balanced, and the first interphase relay, the second interphase relay and the third interphase relay are all switched off, C is Ca (1);
when the three-phase power factor is seriously unbalanced, the first phase-to-phase relay and the second phase-to-phase relay are switched on, the third phase-to-phase relay is switched off, and C is Ca + Cb + Cc (2);
when the three-phase power factors are unbalanced, the permutation and combination conditions of (delta lambda a, delta lambda b and delta lambda c) and the corresponding on-off combination of the interphase relays are known based on the fuzzy rule of the stepless power factor adjustment. It can be seen that when the three-phase power factor is unbalanced, the three-phase power factor has 2 inter-phase relay on-off combinations, namely: the first interphase relay is switched on, the second interphase relay and the third interphase relay are switched off, and C is Ca + Cb (3); and the second method comprises the following steps: when the first interphase relay and the second interphase relay are turned off and the third interphase relay is turned on, C is Ca + Cc (4).
In the step, the three-phase access capacitance value is adjusted by controlling the on-off of the first interphase relay, the second interphase relay and the third interphase relay, and then power interphase compensation is realized.
S4, obtaining a compensation duty ratio of the corresponding phase solid state relay based on the target duty ratio and the actual target duty ratio of the solid state relay A, the solid state relay B and the solid state relay C, performing feedback compensation on the duty ratio of the corresponding phase solid state relay based on the compensation duty ratio to realize accurate adjustment of the duty ratio of the phase solid state relay, and further realizing stepless adjustment of the three-phase power factor. The method specifically comprises the following steps:
s201, calculating target duty ratios of the single-phase solid-state relay based on the single-phase power triangle and the phase capacitance reactive power formula, and obtaining the target duty ratios of the solid-state relay A, the solid-state relay B and the solid-state relay C by adopting the same calculation principle;
s202, obtaining a three-phase compensation coefficient based on a power factor stepless regulation fuzzy rule, wherein the product of the single-phase compensation coefficient and the difference value of the actual power factor and the target power factor of the phase is the compensation duty ratio of the phase, and further the compensation duty ratios of a solid-state relay A, a solid-state relay B and a solid-state relay C are obtained;
s203, the sum of the target duty ratio of the three-phase solid-state relay and the compensation duty ratio of the three-phase solid-state relay is the actual target duty ratio of the three-phase solid-state relay, and the controller accurately controls the three-phase solid-state relay based on the actual target duty ratio, so that stepless regulation of the three-phase power factor is achieved.
Taking phase a as an example, the power triangle before and after phase a power factor is increased is shown in fig. 2. In the context of figure 2, it is shown,
Figure BDA0002962500550000121
is the actual phase angle of the a-phase,
Figure BDA0002962500550000122
is the target phase angle of phase A. Pa is active power of A phase, QlaFor the a phase inductive reactive power, Qca is the reactive power incorporated into the capacitor. QaTo target power factor with phase A
Figure BDA0002962500550000123
Corresponding reactive power. The target duty cycle of the solid-state relay A is recorded as DagoalThe actual target duty ratio of the solid-state relay A is recorded as Dainit. As can be seen from fig. 2, the reactive power Qca of the a-phase capacitor is:
Figure BDA0002962500550000124
the reactive power formula of the capacitor is as follows:
Figure BDA0002962500550000125
wherein tona represents the conducting time of the solid-state relay A in one period T,xca is A phase access capacitance impedance, Ua is A phase voltage effective value, w is A phase voltage current angular velocity, C is A phase access equivalent capacitance;
in the combined type (5) and the formula (6), the target duty ratio of the solid-state relay a can be obtained as follows:
Figure BDA0002962500550000131
taking duty ratio compensation of the solid-state relay a as an example, the compensation principle is shown in fig. 3. The compensation duty ratio is equal to the product of a compensation coefficient and the difference value of the actual power factor and the target power factor, wherein the compensation coefficient is obtained according to the power factor stepless regulation fuzzy rule. Namely:
ΔDa＝ka·Δλa (8)；
wherein, Δ DaIs the compensation duty cycle of the solid state relay A; k is a radical ofaThe A-phase compensation coefficient is obtained according to the power factor stepless regulation fuzzy rule.
As can be seen from fig. 3: the sum of the compensation duty cycle and the target duty cycle of the phase solid state relay is equal to the actual target duty cycle of the phase solid state relay. Namely:
Dainit＝Dagoal+ΔDa (9)；
the controller accurately controls the solid-state relay A based on the actual target duty ratio of the solid-state relay A. The duty ratio of the solid-state relay A is adjusted, the size of the capacitance value of the phase A is adjusted, and the stepless adjustment of the capacitance of each phase is realized, so that the stepless adjustment of the phase A power factor is realized.
As shown in fig. 4, the stepless adjustment fuzzy rule according to the power factor can obtain: when Δ λ a is L, kaIs taken as kal(ii) a When Δ λ a is M, kaIs taken as kam(ii) a When Δ λ a is H, kaIs taken as kah；kal、kam、kahIs constant and 0 < kal＜kam＜kah；
When Δ λ b is L, kbIs taken as kbl(ii) a When delta lambdaWhen b is M, kbIs taken as kbm(ii) a When Δ λ b is H, kbIs taken as kbh；kbIs a B-phase compensation coefficient; k is a radical ofbl、kbm、kbhIs constant and 0 < kbl＜kbm＜kbh；
When delta lambdacWhen is L, kcIs taken as kcl(ii) a When delta lambdacWhen is M, kcIs taken as kcm(ii) a When delta lambdacWhen is H, kcIs taken as kch；kcC phase compensation coefficient; k is a radical ofcl、kcm、kchIs constant and 0 < kcl＜kcm＜kch。
The beneficial effect of this embodiment does: the method comprises the steps of carrying out fuzzy classification on the difference value between a target power factor and an actual power factor of three phases, judging the balance condition of the three-phase power factors according to simulation classification, carrying out three-phase power interphase compensation according to the balance condition of the three-phase power factors, determining the compensation coefficients of a solid-state relay A, a solid-state relay B and a solid-state relay C, and providing a data base for accurately controlling the solid-state relay A, the solid-state relay B and the solid-state relay C;
when the three-phase power factor is unbalanced or seriously unbalanced, the three-phase access capacitance value is adjusted by controlling the on-off of the first interphase relay, the second interphase relay and the third interphase relay, so that power interphase compensation is realized;
the access capacitance is adjusted by controlling the duty ratio of the solid-state relay A, the solid-state relay B and the solid-state relay C, and the stepless adjustment of the access capacitance is realized, so that the stepless adjustment of the power factor is realized;
and a compensation coefficient and a compensation duty ratio of the three-phase solid-state relay are obtained based on a power factor stepless regulation fuzzy rule, and the duty ratio of the solid-state relay A, the solid-state relay B and the solid-state relay C is controlled by a closed-loop control method of compensation duty ratio feedback regulation, so that the accurate control of the duty ratio of the solid-state relay is realized.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (9)

1. The utility model provides a stepless compensation arrangement of pull-out type low-voltage switchgear power factor, its includes controller, electric capacity group A, electric capacity group B and electric capacity group C, its characterized in that: the system also comprises a solid-state relay A, a solid-state relay B, a solid-state relay C, a first interphase relay, a second interphase relay and a third interphase relay;
the inlet wire end of the phase A of the low-voltage switch cabinet is connected with the input end of the capacitor bank A through the solid-state relay A, and the output end of the capacitor bank A is connected with a zero line; the input end of the phase B of the low-voltage switch cabinet is connected with the input end of the capacitor bank B through the solid-state relay B, and the output end of the capacitor bank B is connected with a zero line; the input end of the phase C of the low-voltage switch cabinet is connected with the input end of the capacitor bank C through the solid-state relay C, and the output end of the capacitor bank C is connected with a zero line;
the first interphase relay is connected in parallel between the input end of the capacitor bank A and the input end of the capacitor bank B; the second phase relay is connected in parallel between the input end of the capacitor bank B and the input end of the capacitor bank C; the third phase-to-phase relay is connected in parallel between the input end of the capacitor bank A and the input end of the capacitor bank C;
the controller controls the on-off of the solid-state relay A, the solid-state relay B, the solid-state relay C, the first interphase relay, the second interphase relay and the third interphase relay.
2. The draw-out low-voltage switchgear power factor stepless compensation device according to claim 1, characterized in that: the power factor compensation drawer is also included;
the power factor stepless compensation device is arranged in the power factor compensation drawer; the power factor compensation drawer is installed in a push-pull mode.
3. A method for stepless compensation of power factors of a draw-out type low-voltage switch cabinet is characterized by comprising the following steps: the method comprises the following steps:
s1, connecting according to the connection mode of claim 1;
s2, the controller carries out fuzzy classification according to the difference value of the target power factor and the actual power factor of the three phases at the inlet end of the low-voltage switch cabinet in each control period, and judges the balance condition of the three-phase power factors according to the simulation classification;
s3, when the three-phase power factor is unbalanced or seriously unbalanced, controlling the on-off of a first interphase relay, a second interphase relay and a third interphase relay based on a power factor stepless regulation fuzzy rule to realize three-phase power factor interphase compensation;
s4, obtaining a compensation duty ratio of the corresponding phase solid state relay based on the target duty ratio and the actual target duty ratio of the solid state relay A, the solid state relay B and the solid state relay C, performing feedback compensation on the duty ratio of the corresponding phase solid state relay based on the compensation duty ratio to realize accurate adjustment of the duty ratio of the phase solid state relay, and further realizing stepless adjustment of the three-phase power factor.
4. The draw-out low-voltage switchgear power factor stepless compensation method according to claim 3, characterized in that: the specific rule of fuzzy classification in S2 is:
the difference between the actual power factor of the A phase and the target power factor is recorded as delta lambdaaIt is divided into three fuzzy values H, M, L when the delta lambda isa∈(a1,a2]When, delta lambdaaIs L; when delta lambdaa∈(a2,a3]When, delta lambdaaIs M; when delta lambdaa∈(a3,a4]When, delta lambdaaIs H; a1, a2, a3 and a4 are constants between (0 and 1), and a1 < a2 < a3 < a 4;
the difference between the actual power factor of the B phase and the target power factor is recorded as delta lambdabIt is divided into three fuzzy values H, M, L when the delta lambda isb∈(b1,b2]When, delta lambdabIs L; when delta lambdab∈(b2,b3]When, delta lambdabIs M; when delta lambdab∈(b3,b4]When, delta lambdabIs H; b1, b2, b3 and b4 are constants between (0 and 1), and b1 is more than b2 and more than b3 is more than b 4;
the C-phase actual power factor is compared with the target powerThe difference in the rate factors is recorded as Δ λcIt is divided into three fuzzy values H, M, L when the delta lambda isc∈(c1,c 2]When, delta lambdacIs L; when delta lambdac∈(c2,c3]When, delta lambdacIs M; when delta lambdac∈(c3,c4]When, delta lambdacIs H; c1, c2, c3 and c4 are constants between (0 and 1), and c1 < c2 < c3 < c 4.
5. The draw-out low-voltage switchgear power factor stepless compensation method according to claim 4, characterized in that: in S2, based on the fuzzy classification rule, (Δ λ)a，Δλb，Δλc) There are 27 permutation combinations; wherein, when Δ λa，Δλb，ΔλcAll being a combination of fuzzy values of L, or Δ λa，Δλb，ΔλcWhen the value of (1) is any one combination of two value conditions of the M fuzzy value and the H fuzzy value, judging that the three-phase power factor is balanced;
when delta lambdaa，Δλb，ΔλcWhen two terms are L fuzzy values and the other term is H, the three-phase power factor is judged to be seriously unbalanced;
when delta lambdaa，Δλb，ΔλcIn the case of the remaining combinations, the determination factor is unbalanced.
6. The draw-out low-voltage switchgear power factor stepless compensation method according to claim 5, characterized in that: the method for realizing the A-phase power factor interphase compensation in the S3 comprises the following steps: in an initial state, the controller controls the solid-state relay A to be switched on, the solid-state relay B and the solid-state relay C to be switched off, the equivalent capacitance value of the switched-in phase A is recorded as C, and the capacitance value of the capacitor bank A is recorded as CaAnd the capacitance value of the capacitor group B is marked as CbThe capacitance value of the capacitor group C is marked as Cc；
When the three-phase power factor is balanced, the first interphase relay, the second interphase relay and the third interphase relay are all switched off, and C is equal to Ca；
When the three-phase power factor is seriously unbalanced, the first interphase relay and the second interphase relayThe two-phase relay is switched on, the third phase relay is switched off, and C is equal to Ca+Cb+Cc；
When three-phase power factor is unbalanced, the make-and-break combination of first interphase relay, second interphase relay and third interphase relay has 2, the first: the first phase relay is switched on, the second phase relay and the third phase relay are switched off, and C is equal to Ca+Cb(3) (ii) a And the second method comprises the following steps: when the first phase relay and the second phase relay are switched off and the third phase relay is switched on, C is equal to Ca+Cc。
7. A draw-out low-voltage switchgear power factor stepless compensation method according to any one of claims 4-6, characterized in that: the S4 specifically includes the following steps:
s201, calculating target duty ratios of the single-phase solid-state relay based on the single-phase power triangle and the phase capacitance reactive power formula, and obtaining the target duty ratios of the solid-state relay A, the solid-state relay B and the solid-state relay C by adopting the same calculation principle;
s202, obtaining a three-phase compensation coefficient based on a power factor stepless regulation fuzzy rule, wherein the product of the single-phase compensation coefficient and the difference value of the actual power factor and the target power factor of the phase is the compensation duty ratio of the phase, and further the compensation duty ratios of a solid-state relay A, a solid-state relay B and a solid-state relay C are obtained;
s203, the sum of the target duty ratio of the single-phase solid-state relay and the compensation duty ratio of the single-phase solid-state relay is the actual target duty ratio of the phase solid-state relay, and the controller accurately controls the phase solid-state relay based on the actual target duty ratio, so that stepless regulation of the three-phase power factor is achieved.
8. The draw-out low-voltage switchgear power factor stepless compensation method according to claim 7, characterized in that: the target duty ratio of the single-phase solid-state relay in the step S201 is:
Figure FDA0002962500540000041
wherein tonThe on-time of a solid state relay of a certain phase in a period T is shown, P is the active power of the phase,
Figure FDA0002962500540000042
for the actual phase angle of the phase,
Figure FDA0002962500540000043
and U is the phase target phase angle, U is the effective value of the phase voltage, w is the angular velocity of the phase voltage current, and C is the phase access equivalent capacitance value.
9. The draw-out low-voltage switchgear power factor stepless compensation method according to claim 7, characterized in that: the three-phase compensation coefficients in S202 are respectively:
when delta lambdaaWhen is L, kaIs taken as kal(ii) a When delta lambdaaWhen is M, kaIs taken as kam(ii) a When delta lambdaaWhen is H, kaIs taken as kah；kaIs A phase compensation coefficient; k is a radical ofal、kam、kahIs constant and 0 < kal＜kam＜kah；
When delta lambdabWhen is L, kbIs taken as kbl(ii) a When delta lambdabWhen is M, kbIs taken as kbm(ii) a When delta lambdabWhen is H, kbIs taken as kbh；kbIs a B-phase compensation coefficient; k is a radical ofbl、kbm、kbhIs constant and 0 < kbl＜kbm＜kbh；
When delta lambdacWhen is L, kcIs taken as kcl(ii) a When delta lambdacWhen is M, kcIs taken as kcm(ii) a When delta lambdacWhen is H, kcIs taken as kch；kcC phase compensation coefficient; k is a radical ofcl、kcm、kchIs constant and 0 < kcl＜kcm＜kch。
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